Chitosan and alginate are two frequently used biomaterials for tissue engineering. In this study, electrospinning technique was applied for their nanofiber fabrications to mimic extracellular environment (ECM). Polyethylene oxide (PEO) was applied to increase viscosities of polymer solutions to obtain nanofibers with appropriate morphologies. To modulate surface properties, a dual jet system was developed to coelectrospin chitosan and alginate nanofibers on one substrate. Because the deposition rates of electrospun fibers linearly correlated to the perfusion rates of polymer solutions, the composition ratios of nanofibers were thus manipulated, which determined both the chemical properties and hydrophobicity of fibrous mats. In vitro cell culture results suggested that the cell morphology highly depended on the fiber composition, and the composite nanofibers demonstrated higher biocompatibility than that on pure fibers. Finally, the degradation of alginate fibers was controlled by the crosslinking process. Reducing calcium ions resulted in partial fiber degradation, by which the composition ratios of nanofibers varied with time. This dynamically changed environment performed a promising property to improve viability of surface cells. Through this tunable system, surface properties of scaffolds can be finely adjusted to benefit tissue engineering applications. (C) 2013 Elsevier Ltd. All rights reserved.